closure

PythonClosure.py

#https://www.programiz.com/python-programming/closure
def print_msg(msg):
# This is the outer enclosing function

    def printer():
# This is the nested function
        print(msg)

    printer()

# We execute the function
# Output: Hello
print_msg("Hello")
def print_msg(msg):
# This is the outer enclosing function

    def printer():
# This is the nested function
        print(msg)

    return printer  # this got changed

# Now let's try calling this function.
# Output: Hello
another = print_msg("Hello")
another()
del print_msg
another()
def make_multiplier_of(n):
    def multiplier(x):
        return x * n
    return multiplier

# Multiplier of 3
times3 = make_multiplier_of(3)

# Multiplier of 5
times5 = make_multiplier_of(5)

# Output: 27
print(times3(9))

# Output: 15
print(times5(3))

# Output: 30
print(times5(times3(2)))
print make_multiplier_of.__closure__
print times3.__closure__
print times3.__closure__[0].cell_contents
print times5.__closure__[0].cell_contents

PythonDecorator.py

#https://www.programiz.com/python-programming/decorator
def first(msg):
    print(msg)    

first("Hello")

second = first
second("Hello")
def inc(x):
    return x + 1

def dec(x):
    return x - 1

def operate(func, x):
    result = func(x)
    return result
  
print operate(inc,3)
print operate(dec,3)
def is_called():
  def is_returned():
    print("Hello")
    return is_returned

new = is_called()

#Outputs "Hello"
new()

def make_pretty(func):
    def inner():
        print("I got decorated")
        func()
    return inner

def ordinary():
    print("I am ordinary")

ordinary()

pretty = make_pretty(ordinary)
pretty()


pretty = make_pretty(ordinary)
ordinary = make_pretty(ordinary)

@make_pretty
def ordinary():
    print("I am ordinary")
def ordinary():
    print("I am ordinary")
ordinary = make_pretty(ordinary)

def divide(a, b):
    return a/b
divide(2,5)
divide(2,0)

def smart_divide(func):
   def inner(a,b):
      print("I am going to divide",a,"and",b)
      if b == 0:
         print("Whoops! cannot divide")
         return

      return func(a,b)
   return inner

@smart_divide
def divide(a,b):
    return a/b
  

divide(2,5)

divide(2,0)

def works_for_all(func):
    def inner(*args, **kwargs):
        print("I can decorate any function")
        return func(*args, **kwargs)
    return inner
  
  
  
  def star(func):
    def inner(*args, **kwargs):
        print("*" * 30)
        func(*args, **kwargs)
        print("*" * 30)
    return inner

def percent(func):
    def inner(*args, **kwargs):
        print("%" * 30)
        func(*args, **kwargs)
        print("%" * 30)
    return inner

@star
@percent
def printer(msg):
    print(msg)
printer("Hello")


@star
@percent
def printer(msg):
    print(msg)
    
def printer(msg):
    print(msg)
printer = star(percent(printer))


@percent
@star
def printer(msg):
    print(msg)